1. Field of the Invention
The present invention relates to channel detectors of signal processing receivers, and, in particular, to calibrating parameters used by such channel detectors.
2. Description of the Related Art
In conventional hard-disk drive (HDD) systems, binary ones and zeros are written to HDD platters as magnetic flux reversals. To read the ones and zeros from the disk, a conventional read head detects voltage peaks imparted on the read head when a flux reversal passes underneath the read head. A push by HDD system manufacturers to increase the amount of data that may be stored on HDD platters (i.e., increase the storage density) has resulted in packing data more closely together on the HDD platters. Increasing storage density results in pushing peaks closer together, making it more difficult for HDD systems to detect flux reversals. To combat this issue, partial-response maximum-likelihood (PRML) methods were developed. Rather than looking for peaks, PRML methods sample the analog waveform that the read head detects from the platter. Then, PRML methods use signal processing technologies, such as error detection and error correction, to determine the bit pattern represented by the waveform. As a result of these signal processing technologies, HDD systems that employ PRML methods are typically capable of interpreting smaller changes in the analog signal than equivalent HDD systems that use peak detection. This allows data to be packed closer together, thereby increasing storage densities, while maintaining or even possibly improving error rates of HDD systems.